Equivalent-Circuit Models for Efficient Transmission and Dispersion Analyses of Multi-State Periodic Structures

Abstract

Abstract-An equivalent-circuit model for a reconfigurable unit cell is proposed. This circuit model facilitates fast prediction of scattering parameters and dispersion analyses of a reconfigurable periodic structure. The cutoff frequencies obtained using equivalent-circuit models are in excellent agreement with those from measurements and full-wave numerical simulations. The proposed circuit model is then modified to include non-ideal, commercial RF FET switches. The effect of such a switch in each state, On or Off, is modeled by a frequency-dependant impedance, derived from the scattering parameters of the switch. The proposed technique can be used to analyze a reconfigurable periodic structure with any type of switches. For the structure with 24 unit cells considered here, the equivalent circuit model is about five orders of magnitude faster than full-wave simulations.

Bandstop Filter Synthesis Scheme for Reactively Loaded Microstrip Line Based 1-D Periodic Structures

“…The comparison shows the advantage of the proposed method in synthesizing the physical dimensions of the considered EBG structure. The equivalent circuit model presented in [18] offers greater accuracy than the proposed method. However, circuit models approximations are more useful as an analysis tool than a synthesis tool as they offer limited information in determining the physical dimensions of the structure.…”

“…EBGs can be created in numerous ways. Periodically loading a transmission line with the help of a shorted patch is another approach [17], [18], [20]- [25]. These structures are realized with three metal layers: a sandwich of a patch (layer 2) between the transmission line (on layer 1) and ground plane (layer 3), as shown in Fig.…”

“…However, it is more useful as an analysis tool than a synthesis tool and offers limited help in determining physical structure parameters like widths and lengths etc. to meet a given requirement [17], [18], [26].…”